function JM4 = JMV_9to4(JM9)
k = 0;

%% 二次九节点单元拆分为四个线性单元
for i = 1:length(JM9(:,1))
    %% 1254
    k = k + 1;
    JM4(k,:) = [JM9(i,1), JM9(i,2), JM9(i,5), JM9(i,4)];
    %% 2365
    k = k + 1;
    JM4(k,:) = [JM9(i,2), JM9(i,3), JM9(i,6), JM9(i,5)];
    %% 4587
    k = k + 1;
    JM4(k,:) = [JM9(i,4), JM9(i,5), JM9(i,8), JM9(i,7)];
    %% 5698
    k = k + 1;
    JM4(k,:) = [JM9(i,5), JM9(i,6), JM9(i,9), JM9(i,8)];
end

end